1. Field of the Invention
The present invention relates to an image heating apparatus that can be suitably used as a gloss application apparatus.
2. Description of the Related Art
Electrophotographic image forming apparatuses, such as copiers and printers, are widely known, and many full-color image forming apparatuses are commercially available, in addition to monochrome ones. As the increased use of electrophotographic image forming apparatuses in various fields, the level of requirements on image quality becomes increasingly higher. One determinant factor of image quality, in particular, the gloss level of a full-color image is smoothness of an output image.
A method for improving the smoothness of an output image by use of a recording material including a transparent thermoplastic resin layer is disclosed in Japanese Patent Laid-Open Nos. 64-035452, 5-216322, and 2003-084477.
Japanese Patent Laid-Open Nos. 4-216580, 4-362679, and 2004-109860 disclose a belt fuser configured to press and heat a recording material carrying an unfixed toner image by using a fixing belt including a heat-resistance film, solidify the toner image by cooling the recording material while the recording material is in close contact with the fixing belt, and then separate the recording material from the fixing belt.
When standard-sized recording materials are repeatedly used through such an image forming method, a phenomenon occurs in which foreign matter such as paper powder and a resin component drops from an end of a recording material and attaches to a surface of the fixing belt. The foreign matter may be transferred to an end of the subsequent recording material, causing image defects, and/or the accumulated foreign matter may damage the fixing belt, destroying the durability of the fixing belt.
In addition to the above problems, the inventor et al. finds that, if foreign matter such as paper powder and a resin component dropping from an end of a recording material is attached to and accumulated on the fixing belt, when the subsequent recording material is placed on the fixing belt such that the leading edge of the subsequent recording material overlaps the foreign matter, the separability of the recording material from a conveyance separation portion on the fixing belt significantly decreases.
A belt fuser discussed in Japanese Patent Laid-Open No. 2004-109860 uses a structure in which at least one of opposite side ends of a recording material separated from a fixing belt along the direction of conveyance of the recording material is cut and removed. Therefore, even if foreign matter such as paper powder and a resin component of a recording material attached to and accumulated on the fixing belt is then attached and transferred to an end of the subsequent recording material, the attached foreign matter does not affect an output image by cutting and removing a part of the recording material to which the foreign matter is attached.
However, no consideration is given to leading and trailing ends of the recording material, which are orthogonal to the direction of conveyance of the recording material.